Partners who have been betrayed early in a relationship use regions of the brain associated with controlled, careful decision-making when considering whether they should continue to trust the person who deceived them, according to new Stanford University research.

On the other hand, those betrayed in a long-standing relationship use areas of the brain associated with automatic, habitual decision-making, increasing the likelihood of forgiveness.

For the study, sociologist Karen Cook and her team wanted to understand why some people choose to reconcile after they’ve been betrayed in a relationship, while others decide to leave. They hypothesized that if the relationship was new, the betrayed person would engage in conscious, deliberate problem-solving when deciding how to respond to the deceit. However, if the relationship was already long-term, the victim might take trustworthy behavior for granted and consider the deceit an exception to the rule.

To test their theory, the researchers conducted an online experiment, using participants recruited through an Internet survey provider. Each participant received $8 and could either keep the money or give it to an unseen partner. If the participant gave the money away, its value would triple. The partner would then decide whether to keep it all or give half back to the other person.

Unbeknownst to the study participant, the partner was really a computer, sometimes programmed to betray the person early in the game and sometimes programmed to betray the person later. The findings revealed that after an early betrayal, the subject would be more likely to keep the money than after a betrayal that occurred later.

The researchers repeated the experiment in a laboratory, with participants hooked up to fMRI scanners. They found that the person’s anterior cingulate cortex, associated with conscious learning, planning and problem-solving, and the lateral frontal cortex, associated with feelings of uncertainty, became more active after early betrayal. In contrast, the lateral temporal cortex, associated with habituated decision-making, became more active after late betrayal.

Similar to the first experiment, an early betrayal made the subject more likely to hold onto the money in later rounds. Furthermore, early betrayal increased the amount of time taken to make a decision, suggesting that a victim of early betrayal puts more conscious thought into a decision than a victim of late betrayal.

The researchers hope their study will help reveal why some victims of deceit continue to forgive their deceivers.

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Traci Pedersen

Traci Pedersen is a professional writer with over a decade of experience. Her work consists of writing for both print and online publishers in a variety of genres including science chapter books, college and career articles, and elementary school curriculum.